Chandogya Upanishad 4.7.3

4.7.3

brahmaṇaḥ somya te pādaṃ bravāṇi iti \
bravītu me bhagavān iti \
tasmai ha uvāca \
agniḥ kalā \
sūryaḥ kalā \
candraḥ kalā \
vidyut kalā \
eṣa vai somya catuṣkalaḥ pādo brahmaṇo jyotiṣmān nāma \\407.3\

3. ‘Let me tell you, my dear, a quarter of Brahma.’ ‘Tell me, Sir.’ To him it then said: ‘One sixteenth is fire. One sixteenth is the sun. One sixteenth is the moon. One sixteenth is lightning. This, verily, my dear, is the quarter of Brahma, consisting of four sixteenths, named the Luminous.